Ever since Peter-Paul Koch put online his [quirksmode] web site, his opinions caused quote a stir in web design community. He openly opposes most of the techniques and guidelines many of us advise.
In the Keep it simple column at Digital Web, PPK published an article where he advised developers to avoid the use of hacks, since some new browser version might fix the bug used for hack but not fix the very behavior you are trying to hack.
In the latest article, PPK posted a list of CSS hacks that could be considered safe, since they apply to dead browsers (NN4, IE5/Mac), and dismissing anything else, since the “live” browsers are updated and can fall into a trap he explained in the original article.
I agree with the point about new browser versions and bug fixing. Yes, that can happen. And that’s all I agree with.